Chromosome Engineering Reveals New Locus for Fusarium Resistance in Wheat

Fusarium head blight (FHB) remains one of the most destructive diseases in global wheat production, and its impact is only intensifying. Warmer climates and crop rotations that favor pathogen survival have expanded the prevalence of FHB outbreaks, leading to major yield losses and contamination of grain with mycotoxins such as deoxynivalenol (DON), nivalenol (NIV), and zearalenone (ZEN).

While fungicides offer partial control, reduced sensitivity and rising costs have made genetic resistance in wheat the most sustainable long‑term strategy. Yet despite decades of breeding, only a handful of major FHB resistance loci—Fhb1 through Fhb9—have been formally designated, and just two have been cloned. The scarcity of strong, deployable resistance genes has become a bottleneck for wheat improvement.

A new study published in the Journal of Experimental Botany, “Identification of a novel Fusarium head blight resistance locus Fhb.Er‑1StL from Elymus repens introgressed into wheat,” expands that genetic toolkit. Researchers at Sichuan Agricultural University report the discovery of a previously unknown FHB resistance locus, Fhb.Er‑1StL, derived from the wild grass Elymus repens—a species better known as an agricultural weed than a genomic resource.

“Both research and breeding practice have shown that developing and deploying resistant wheat cultivars is the fundamental solution to FHB,” said first author Fei Wang. “However, current efforts are limited by a scarcity of major resistance sources, narrow genetic backgrounds, and inefficient use of resistance genes.”

The team began by characterizing the genome of a wheat E. repens partial amphidiploid, P1142‑1‑2, which carries the full wheat genome plus seven pairs of alien chromosomes or chromosome fragments. Using sequential GISH and FISH cytogenetics, they mapped the alien chromatin and identified a pair of chromosomes containing the long arm of the E. repens 1St chromosome. From crosses with the susceptible wheat cultivar Chuannong16, they isolated two derivative lines carrying either a 1StL isochromosome or a 1StL telosome, both of which conferred strong resistance to FHB.

To pinpoint the resistance locus, the researchers applied a targeted sequencing approach using the Wheat–St 45K liquid microarray GBTS platform. This allowed the researchers to precisely identify the alien 1StL segment and develop markers to track it in breeding lines. Plants carrying this segment showed markedly improved resistance, and molecular assays confirmed that the region represents a previously unknown FHB resistance locus, now designated Fhb.Er‑1StL.

“We believe this work is of practical importance for accelerating the breeding of resistant, high‑yielding wheat varieties and breaking the bottleneck in FHB resistance breeding,” said senior author Yinghui Li, PhD.

Next steps include fine‑mapping the locus and generating smaller translocation lines to reduce linkage drag—an essential step before the trait can be widely deployed in commercial breeding.

“With the aid of modern genomic technologies and precise breeding strategies, Fhb.Er-1StL holds promise as a cornerstone for developing next-generation wheat cultivars with durable resistance to FHB,” concluded the authors.

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